Synthesis and Photophysics of Silicon Phthalocyanine–Perylenebisimide Triads Connected through Rigid and Flexible Bridges

Abstract

Three new bisperylenebisimide-silicon phthalocyanine triads [(PBI)(2)-SiPcs 1, 2, and 3] connected with either rigid or flexible bridges were synthesized and characterized. A new synthetic approach to connect SiPc and PBI moieties through click chemistry produced triad 3 with an 80% yield. In (PBI)(2)-SiPc 1, PBI and SiPc are orthogonal and were connected with a rigid connector; triads 2 and 3 bear flexible aliphatic bridges, resulting in a tilted (2) or nearly parallel arrangement (3) of PBI and SiPc. Photoinduced intramolecular processes in these (PBI)(2)-SiPcs were studied and the results are compared with those of the reference compounds SiPc-ref and PBI-ref. The occurrence of electron-transfer processes between the SiPc and PBI units was confirmed by time-resolved emission and transient absorption techniques. Charge-separated (CS) states with lifetimes of 0.91, 1.3 and 2.0 ns for triads 1, 2, and 3, respectively, were detected using femtosecond laser flash photolysis. Upon the addition of Mg(ClO(4))(2), an increase in the lifetime of the CS states to 59, 110 and 200 μs was observed for triads (PBI)(2)-SiPcs 1, 2, and 3, respectively. The energy of the CS state (SiPc(·+)-PDI(·-)/Mg(2+)) is lower than the energy of both silicon phthalocyanine ((3)SiPc*-PDI) and perylenebisimide (SiPc-(3)PDI*) triplet excited states, which decelerates the metal ion-decoupled electron-transfer process for charge recombination to the ground state, thus increasing the lifetime of the CS state. The photophysics of the three triads demonstrate the importance of the rigidity of the spacer and the orientation between donor and acceptor units.

Zinc Phthalocyanine–Graphene Hybrid Material for Energy Conversion: Synthesis, Characterization, Photophysics, and Photoelectrochemical Cell Preparation

“…75,76 This band is known to be broadened by strong π--π interac--tions. 65 Therefore, no observation of the absorption band at 840 nm in Figure 6a together the red shift and broad--ening of the absorption band in Figure 4 suggests strong π--π interactions of ZnPc •+ with graphene. Although this interpretation has yet to be clearly proven, the time pro--file of transient absorption at 620 nm clearly consists of two steps (Figures 6b and 6c), 77 which may well be as--signed to the charge separation to form the charge--separated state (ZnPc •+ -graphene •-) and the charge re--combination, judging from the observation of the charge--separated state by EPR measurements (vide infra).…”

Modern Synthetic Tools Toward the Preparation of Sophisticated Phthalocyanine‐Based Photoactive Systems

“…In a similar outlook, Sastre‐Santos, Fernández‐Lázaro et al. described an elegant D–A SiPc‐PDI triad ( 103 ) obtained by a “click” approach 87. As shown in Scheme , SiPc 101 substituted with two axial terminal alkynes was subjected to “click” conditions in the presence of azide‐substituted PDI 102 .…”

Energy transfer in pendant perylene diimide copolymers

“…Sensitiser and acceptor perylene-acrylate monomers were synthesised using modified literature procedures, starting from commercially available 3,4,9,10-perylenetetracarboxylic dianhydride [36][37][38][39][40] (Figures 1 and 2). Creation of a polymer pendant group based on the PDI center requires an asymmetric PDI monomer.…”